This invention relates generally to antennas for transmitting and receiving electromagnetic waves, and more particularly the invention relates to a circularly or elliptically polarized omnidirectional antenna having a balanced feed.
A number of antennas and antenna designs are known for transmitting RF electromagnetic signals. In FM radio broadcasting, for example, antennas are designed for broadcasting in a frequency range of 88 MHz to 108 MHz in channels of 200 KHz width. The antennas are typically omnidirectional for broadcast in all directions, although directional antennas are known and can be employed where directivity is desired.
In addition to providing an antenna designed to accomplish omnidirectional broadcast of a circularly-polarized wave, the feed of electrical signals to the radiating elements is important in providing balanced excitation to the radiating elements, minimal excitation of the support structure and other nonradiating elements, and generally efficient power transfer from input power to radiated power.
The present invention is directed to an improved omnidirectional antenna and feed for efficiently providing a balanced drive to the radiating elements of the antenna.